If you need to make a rewrite rule on your .htaccess file, for example a condition if a URL not contains an string, you will need to make the following:

• Before we begin generating the actual URL rewrites, we need to activate the apache mod_rewrite module that controls them. Lets type in your terminal:
  
  1	sudo a2enmod rewrite

• Edit (or create) an .htaccess file on your project root:
  
  1	sudo nano /var/www/site.com/.htaccess

• Those are some examples of what you can get done with your .htaccess file:
  
  1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

  <IfModule mod_rewrite.c>     RewriteEngine On     RewriteCond %{REQUEST_FILENAME} !-f # redirect all from ^find-your-prod.aspx to find-your-prod.php     RewriteRule ^find-your-prod.aspx find-your-prod.php [QSA,L]         # redirect all from find-your-prod.php to find-your-prod (remove .php)     RewriteRule ^find-your-prod.php(.*)$ /find-your-prod$1 [L,R=302]     # If url not contains string (CONDITION IS TRUE) then, redirect # => if url not contains /catalog/seo_sitemap/category redirect to /html-catalog     RewriteCond %{REQUEST_URI} !^/catalog/seo_sitemap/category(/|$)       RewriteRule ^catalog(.*)$ /html-catalog$1 [L,R=302] </IfModule>